Earth boring drill



Aug- 25, 1959 FQ L. sco'r-r 2,901,223

. EARTH BQING DRILL Filed Nov. 30, 1955 /r/ogc/ l. Sco/ JNVENTOR.

United States Patent Office Patented Aug. 25, 1959 EARTH BORING DRILL ApplicationNovember 30, 1955, Serial' No. 549,969

3 Claims. (Cl. Z55-302) This invention relates to earth boring tools and more particularly to a well drill or bit of the rotating cutter type which is of particular utility in drilling relatively soft formations.`

In the drilling of well bores, by the rotary method of drilling and in earth Iformations which are relatively soft, difhculty has been experienced from. clogging or balling up of bits when a high rate of penetration is attempted. It` appears that this diiculty arises primarily from the facts that the drill bit structure provides insuicient ventilation to permit `immediate removal of cuttings when formed andthe cuttings `are' insufcient comminuted to facilitate such removal from the cutting area.

Earth formations, of the typeto which reference is abovemade,` are most commonly encountered at shallow depths lbut extend? to considerable depths in certain regions such, for example,fas theGulf Coast and tidelands areas of the United States. These `formations are of a nature that they are relatively deformable under pressures such as those applied when drilling by the rotary method.l It is customary that lan earth boring` drill of the rolling cutter type shall be so` designed that the cutting action of the rolling cutters shall cover the entire bottom of the hole being drilled and each cutter shall be in close contiguity with the adjacent cutters, usuallywith the teeth of adjacent cutters interftting. The present invention is Abasedupon the discovery that it is possible to. drill more rapidly, especially in the softer, and hence deformable, formations, bymeans of a bit' in which the rolling cutters are spaced relative to each other. and do not produce cutting action upon the entire" bottom of;` the hole being drilled, means being provided inthe =bit`t`o` remove cuttings 4formed by the cutters, to desirably disintegrate all formation material deformed' orextruded by the bit and also to remove the cor'ewhich forms" on that portion of the hole bottom not covered by the cutters. A bit constructed in accordance with the invention also provides adequate ventilation that the cuttings are effectively removed from the cutting zone.

It is the primary object of the invention to provide a well drill capable of drilling earth formations at a high rate of penetration.

Another object is to provide a Well drill of the rolling cutter type in which the cutters are spaced outwardly of the axis of the well bore being drilled, the drill including means for removing cuttings Ifrom bottom and for disintegrating and removing the formation material which tends to Iform a core at the center of the well bore.

Still another object is to provide a well drill or bit in which the ilushing -lluid is so directed as to disintegrate formation material at and proximate the center of the well bore and to effectively initiate upward movement of such material together with that disintegrated by the cutters.

A still further object is to provide a rolling cutter type of bit of the class described in which the action of the cutters, spaced outwardly of the axis of the bit, is supplemented by a nozzle assembly lfrom which uid is discharged at a high velocity to effect disintegration of formation material to be removed from the cutting area.

These and other objects will be more Ifully apparent from. the following description, considered in connection with the accompanying drawings in which:

tFifg'.- l is an' elevational: view of a wel-l drill of the three-cone-cutter type embodying the invention, a portion of the' drill beingcut away to show lthe internal construction;

Fig. 2 is a bottom view of the well drill, a circle beingdrawn to show the periphery of a hole drilled by the bit;`

Fig. 3 is a side elevational view of the well drill within a Ibore hole being formed thereby, such view illustrating the manner in which the flushing iluid? disintegrates the earth.v -formation material at the center of the hole including that which is deformed or extruded by the rolling` cutters from pressure applied to the cutters during drilling.

The` illustrated embodiment is aA three-clone drill or bit although itl is toy be understood that the invention is equally applicable whether the numberl of cutters is greater or less than shown. The bit comprises a head 1 havinga threaded shank 2 for attachment to a drill string or stern (not shown). The bit head 1 includes the downwardly extendingv legs 3 each of which is: provided with an inwardly extending cantilever shaft (not shown) upon whichf. is rotatably mounted arolling cutter 4 as is Well known in the art. Also as is customary each cutter is provided with cuttingy elements or teethl 5 of suitable designr andi spacing as to effectively penetrate and disintegrate,` that portion of therbottom of the hole that is traverse'd` by the cut'tersasl the bit is rotated.

Asti already explained it is usual for the cutters of a well'drill to: effect their cutting action from the center to the periphery of the hole Kbeing drilled and also for each cutter to be closely contiguous to the adjacent cutters. In accordance with the present invention such is not the'. case as` the cutters 4 are of such size that their innermost cutting elements. identied as 6, 7 and 8 are located outwardly for the bit axis. At the same time the cutters are quite` widely separated circumferentially of thefbit` and this arrangementprovides wide spacing at the heels, or bases` of the cone shaped cutters, as shown at 1.0 in^ Fig. 2, so that flushing iluid has an opportunity to remove cuttings from :bottom and upwardly past the cutters 4fand the bit head 1 whence they move upwardly and are discharged from the Well bore at the surface. While the cutters 4 are shown with the peripheries of adjacent cutters in converging relation in the plane where such adjacent cutters are most closely contiguous, itis to be understood that the angle of convergence, or divergence, may be desirably varied by changing the vertex angle of the cone defined by the respective frusto-conical cutters. That is to say, the peripheral configuration of the cutters, and the cutting elements thereon, may be varied as desired in order to adapt the bit to drilling most effectively in various types of formations.

Wide spacing of the cutters gives rise to the tendency for the cutters 4 to produce an annular kerf and a central upstanding core at the center of the well bore. An important feature of the invention resides in the cooperative action between the cutting structure thus far described and a novel core breaker and nozzle assembly 12 which will now Ibe described.

This assembly comprises a body 13 reduced at its upper end at 14 and seated within a complemental counterbore 15 at the lower end of the central `bore 16 in the bit head 1. It is integrally united to the bit head by a bead of weld metal shown at 17.

fhe body 1,3 has three hollow, sidewardly extending bosses 18 each of which is provided with a wear resistant nozzle 19 secured within its lower end. Preferably, and as shown, the assembly 12 is so oriented .about the axis of the bit that fluid discharged from the nozzles 19 forms jets which are directed downwardly and outwardly approximately midway between successive cutters 4.

Attached to the body 13 and extending downwardly therefrom is a projection 20 provided with radially extending ns 21 whose lower ends are adapted to function as a cutter. This projection may be tapered to a point at its lower end which is proximate the inner ends of the rolling cutters, it being intended that this structure shall be capable of breaking up any core that forms and extends centrally upward vfrom the bottom of the Well bore formed by the bit. As will appear from the further description of operation of the bit it has been -found that the projection 20 and -iins 21 thereon have a minor function to perform, this feature of construction merely serving to assure that any core that forms shall not assume proportions that will retard drilling action.

Experience reveals that the bit of the invention is capable of drilling approximately 30% to 40% faster than conventional bits of types heretofore used, and at the same time is relatively immune from balling up. It has also been found in bits embodying the invention that, even after Idrilling in excess of 5,000 feet of hole, the projection 20 is in substantially new condition.

Applicant is uncertain as to reason for the unusual operating characteristics of the bit but believes that a Ilogical explanation is illustrated in Fig. 3. As already indicated, relatively soft lformations for which the bit is best adapted are quite deformable under pressure, it is therefore, believed that while the cutters 4 apply pressure to and effect cutting action on bottom and produce cuttings as indicated at 25 the weight applied to the bit also causes extrusion of formation material toward the center of the hole 26 and also toward the spaces 10 intermediate the cutters as indicated by the arrows 28. At the same time a core tends to form centrally of the hole but such core is penetrated by the projection 21 and thence sloughs outwardly whence the core material joins the cuttings 25 and the extruded material 28. The jets from the nozzles 19 are of relatively high velocity, of the order of 200 -feet per second or greater. Hence, the downwardly projected uid jets possess suicient energy to produce a slashing action (as illustrated in Fig. 3) upon the formation materials displaced from the bottom of the hole being drilled. Also, disintegration of such materials is effected and movement upward from the cutting zone is initiated. t

Broadly the invention comprehends an earth boring drill of the rolling cutter type which is of particular utility in the drilling of relatively soft earth formations and capable of a high rate of penetration.

The invention claimed is:

r1. A drill bit including, a head having a plurality of depending legs, a shaft extending inwardly and downwardly from eac-h of said legs, a rolling cutter rotatably mounted upon each of said shafts, each of said rolling cutters extending a portion of the distance from the periphery of the bit toward the axis of the bit and enclosing the inner end of the associated shaft, there being a passage axially of the bit head, a downward projection on said head axially of the head and intermediate and spaced inwardly from the inner ends of said cutters, said projection terminating in a cutter proximate the inner ends of the rol-ling cutters, a plurality of downwardly directed nozzles about said projection and at the base thereof arranged to direct flushing iluid from said passage and upon bottom of the hole and intermediate said rolling cutters whereby formation material is disintegrated and moves upwardly with the flushing iluid from the bottom of the hole.

2. A drill in accordance with claim 1 in which the nozzles are positioned to direct fluid upon bottom at points outwardly of the axis of the bit and substantially midway between successive cutters.

3. A drill bit including, a head having a plurality of depending legs, a shaft extending inwardly and downwardly lfrom each of said legs, a rolling cutter rotatably mounted -upon each of said shafts, each of said rolling cutters extending a portion of the distance from the periphery of the bit toward the axis of the bit and enclosing the inner end of the associated shaft, there being a passage axially of the bit head, a nozzle assembly secured to the bit head at the lower end of said passage, said assembly including a downwardly extending projection extending axially of the bit and terminating in a cutter proximate the inner ends of the rolling cutters, and a plurality of downwardly and outwardly directed nozzles arranged about said projection to direct flushing uid from the passage and upon the bottom of the holle at points spaced outwardly between the rolling cutters intermediate the axis and periphery of the hole.

References Cited in the le of this patent UNITED STATES PATENTS Re. 23,416 Kinnear Oct. 16, 1951 2,200,482 Winslow May 14, 1940 2,320,136 Kammerer May 25, 1943 2,358,642 Kammerer Sept. 19, 1944 2,540,464 Stokes Feb. 6, 1951 2,661,931 Swart Dec. 8, 1953 2,692,117 Kucera et al. Oct. 19, 1954 2,751,196 Smith June 19, 1956 

